Question

An electrical heater is rated 4kW,220V. Calculate(i) the current(ii)resistance of the heater(iii)enrgy consumed in 2h(iv)total cost if 1kWh is charged at Rs.0.50.

Please explain the steps.

Answer 1

 Power P = 4 kW, V= 220 V P = VI.
Therefore current I = P/V
                              = 4 kW/220 V 
                              = 4000 W/220 V 
                              = 18.18 AResistance of the heater R = V/I
                                            = 220 V/18.18 A
                                             = 12.1 Ω. Energy consumed in 2h = Pt
                                       = 4 kW x 2h
                                       = 8 kWh.If cost of 1 kWh = Rs. 1.50,
then cost of 8 kWh of energy = Rs. 1.50 x 8 
                                               =  Rs.12.00